1. Field of the Invention
The present invention concerns image reading apparatus. More specifically, it is concerned with image acquisition apparatus with functions to evaluate the image quality of scanned images.
2. Description of the Related Art
Paper documents (documents, or copy) can be put into electronic form and saved by reading them by a scanner (scanning). In such circumstances, it is desirable that the digitized documents are complete copy of the original documents. For that purpose, where the color tone, resolution or the like are the main concern, it may be better to scan all documents using multi level color and at high resolution as well, but under real conditions the copy will be a mixture of color or monochrome, and the content of the text will be a mixture of characters and photography, and it is not necessarily any reason for scanning the entire document using multi level color and high resolution. Performing a scan of such documents using both multi level color and high resolution can end up consuming more resources than necessary, such as work time or data storage.
While is it desirable from the point of view of reproducibility of the text to scan using multi level color and high resolution, it is also desirable from the point of view of work time and efficient utilization of resources to scan using binary monochrome and low resolution. Accordingly, in normal scanning work, the user enters scanning operation parameters such as resolution, and color or monochrome, for each scanning job. However, when the user inputs unsuitable operation parameters, leading to indistinct photographs and detailed characters and the like, there is the problem that the quality of the scanned image (henceforth, “scan quality”) ends up being reduced. For this reason, it becomes necessary to verify the scan quality after the operation (to verify whether or not the parameters entered by the user were appropriate), but the verification of scan quality will depend on immediate user perception of the scan condition. However, inspection by users is labor-intensive, and because it relies on the user, the quality or lack thereof for each user can be ambiguous, resulting in the problem of inconsistencies in judgment about the quality of scanned images, especially when there is more than one user, scanning many pages.
As a technique for solving these sorts of problems, in patent reference 1, a technique is disclosed for checking the file format of the image data scanned and outputting the check results in a chart. As well, in patent references 2 and 3, techniques are disclosed for scanning documents that have been output using image output devices such as printers and verifying the efficacy of the image output device by checking the images of the documents. Also, in patent references 4 and 5, techniques for evaluating the quality of image data are disclosed.
Patent Reference 1:                Japanese Laid-open Patent Publication No.: 2002-77468        
Patent Reference 2:                Japan Patent No.: 3160898        
Patent Reference 3:                Japan Patent No.: 3086520        
Patent Reference 4:                Japan Patent No.: 3076692        
Patent Reference 5:                Japanese Laid-open Patent Publication No.: 11-203411        
However, with the technique given in patent reference 1, the checking result is only presented as an image, and when performing a rescan, users are required to rescan after determining quality problems in the document, which is not efficient. As well, the techniques given in patent references 2 and 3 evaluate the special characteristics of image output apparatus using statistical operations or test pattern scanning, but there remains a problem that the scanned images is not evaluated. Furthermore, the scan errors that can be sensed using the image quality evaluation techniques given in patent reference 4 are very limited. As well, there is also the problem that even in checking image data using present-day techniques, users may not improve their technical skills at all. The present invention has been made in view of the above circumstances and provides an apparatus for reading images that improves not only efficiency but scan quality, and with which users can improve their technical skills in scanning.